Operating means for enclosed electric circuit controlling devices



Dec. 28, 1954 E.F.MEKELBURG OPERATING MEANS FOR ENCLOSED ELECTRIC CIRCUIT CONTROLLING DEVICES Filed Sept. 20, 1950 5 Sheets-Sheet 1 2 J ,4? ea 4/ IZ i INVENTOR.

22F; fiwiezzm v FTT /FIY Y.

D 1 4 E. F. MEKELBURG OPERATING MEANS FOR ENCLOSED ELECTRIC I CIRCUIT CONTROLLING DEVICES Filed Sept. 20, 1950 5 Sheets-Sheet 2 F. MEKELBURG OPERATING MEANS FOR ENCLOSED ELECTRIC CIRCUIT CONTROLLING DEVICES Filed Sept. 20, 1950 Dec. 28, 1954 3 Sheets-Sheet 3 IN VEN TOR. ZZ/Z Ffifje! United States Patent Ofiice 2,698,361 Patented Dec. 28, 1954 OPERATING MEANS FOR ENCLOSED ELECTRIC CIRCUIT CONTROLLING DEVICES Earl F. Mekelburg, Wauwatosa, Wis., assignor to Square D Company, Detroit, Mich., a corporation of Michigan Application September 20, 1950, Serial No. 185,699

10 Claims. (Cl. 200-50) This invention relates to a mechanism for operating enclosed circuit controlling instrumentalities.

One object of the present invention is the provision of new and improved mechanism for operating switches, circuit breakers and the like which are mounted within enclosing boxes.

Another object of the present invention is the provision of a device for operating enclosed circuit controlling instrumentalities which are mounted within enclosing boxes having openable doors, the operating mechanism being provided with an operating handle at the exterior of the box to effect operation of the device and with means for locking the handle in predetermined positions to maintain the enclosing box closed and the circuit controlling instrumentality in a particular condition.

Another object of the invention is the provision of a device in accordance with the preceding objects, in which the internal mechanism for operating the circuit controlling instrumentality is provided with resilient means permitting movement of the operating handle beyond the normal off position to facilitate the locking of the device.

Another object of the present invention is the provision of a device in accordance with the preceding objects, in which the operating handle may be locked in the on and the lock positions, the device being so constructed that the door to the enclosing box may be opened with the operating handle in the off position, or with the operating handle in the on position after the operation of suitable disabling means; the operating handle being associated with a locking mechanism which may look the operating handle in either the lock position or the on position, and in both cases prohibit the employment of the disabling means whereby the circuit controlling instrumentality may be locked in either on or off position and the door to the enclosing box locked closed.

Other objects and features of the present invention Will be readily apparent to those skilled in the art from the specification and appended drawings illustrating certain preferred embodiments in which:

Figure l is a front elevational view of the device of the present invention.

Figure 2 is an enlarged sectional view along the lines IIII of Figure 1.

Figure 3 is an enlarged sectional view along the line IIIIII of Figure 1.

Figure 4 is a sectional view along the line 1VIV of Figure 2.

Figure 5 is a of Figure 2.

Figure 6 is a sectional view along the line VI-VI of Figure 2.

Figure 7 is a view from the position of Figure 6 in which the operating handle has been moved to the on position.

Figure 8 is a partial sectional view along the line VIIIVIII of Figure 2.

Figure 9 is an exploded view of one end of the operating shaft and the member operated by the handle which cooperates therewith when the door is closed.

Figure 10 is a modification of the operating mechanism, showing an automatic electric circuit breaker mounted within the enclosing box.

Figure 11 is a side view of the modification shown in Figure 10.

Figure 12 is a partial view similar to Figure 2, with the handle shown locked in lock position.

partial sectional view along the line V-V The device of the present invention is an operating mechanism for circuit controlling instrumentalities which are mounted within enclosing boxes, the boxes generally being made of metal, such as the box 1, and having an outer hinged door 2. As shown in Figure 2, an electric switch 3 having a movable blade 4 which cooperates with suitable contact 5 is mounted in insulated relation upon a back plate 6 which is suitably secured, as by studs, to the back of the enclosing box 1. To actuate the switch, there is provided a rotatable operating shaft 7, connected to the operating handle in a manner to be subsequently explained, the operating shaft 7 having secured to its inner end a lever 8 having bifurcated portions 9 projecting rearwardly therefrom which cooperate with a pin 11 extending through the operating shaft 7 to rigidly mount lever 8 upon shaft 7. The lever 8 extends generally parallel to the back wall of the enclosing box 1 and carries a ledge 12 projecting rearwardly therefrom and being suitably connected to one end of a compression spring 13.

The opposite end of compression spring 13 is suitably secured to one ledge 14 projecting rearwardly from a lever 15 pivotally mounted upon the shaft 7. Lever 15 has a second ledge 16 which normally abuts against the upper surface, from the view of Figure 4, of ledge 12 of lever 8. It will readily appear that lever 15 is directly moved by lever 8, due to the engagement of ledges 12 and 16, as shaft 7 is moved in a clockwise direction from the position of Figure 4. When shaft 7 is rotated in a counterclockwise direction, from the view of Figure 4, the lever 8 effects movement of lever 15 through the medium of spring 13 which, as indicated earlier, is interposed between ledge 12 of lever 8 and ledge 14 of lever 15. It will be seen that this latter type of movement occurs when the switch is moved toward the oif" position, and that the shaft 7 may be rotated past the off switch position against the bias of spring 13 fora purpose to be subsequently explained. i

Pivotally mounted upon the back plate 6 is an operating lever 17 which is operatively connected to a contact operating bail 18 of the electric switch 3 by a pair of levers 19 and 21. Also pivotally connected to the back plate 6 by means of a pivoted bracket 22 is a toggle link 23, an overcenter spring 24 being interposed between the bracket 22 and the main portion of the link 23. Mounted to the base plate 6 behind the lever 17, from the View of Figure 4, is a toggle plate 25 which carries a pin 26 projecting outwardly therefrom, the pin 26 extending through suitable slots in levers 23, 15 and 17, the slots in the latter two levers extending in the direction of relative movement of pin and levers to provide lost motion connections therebetween.

The outer end of shaft 7 carries a male coupling member 29 which is rigidly mounted to the shaft 7 by means of a stud. The coupling member 29 has, as may be seen in Figure 9, a generally conical outer end 31 and a pair of bosses 32, projecting from either side thereof. Depending from member 29 is an arcuate plate 33 having a single aperture 34 in the periphery thereof, which divides the outer edge of plate 33 into two sections, 27 and 28.

Mounted upon the door 2 of enclosing box 1 is the operating lever assembly which includes a female coupling member 35, also shown in Figure 9, disposed behind the inner surface of the door 2, the member 35 having slots 3.6 therein which, when the door 2 is closed,

cooperate with the bosses 32 of the member 29. Member 35 has cutaway edges at 37 at the entrance to each of the slots 36 so that coupling members 29 and 35 are permitted to engage when the door is closed regardless of some original angular misalignment between the bosses and slots of the coupling members, the handle being forced into proper position. Member 35 has an extension 38 which extends through the door 2 of enclosing box and is secured by a stud to a circular, cup-shaped disk 39 which integrally carries an operating handle 41. It will be seen in Figure 8 that the periphery of disk 39 is provided with two apertures 42 and 43, and that the interior of the disk is provided with a spring 44 which acts to bias the operating handle 41 toward a position intermediate the normal on and ofi position.

Mounted between the disk 39 and the surface of the door 2 is a plate. 45 havingv indicia thereon for indicating the condition of the enclosed switch and carrying an integral hub Within which the extension 38 of member 35 rotates. The plate 45 has an integral extensionbelow the disk 39 which has a series ofu-sh'aped projections 46 which extend outwardly perpendicular. to and away from the front surface of the door 2. Contained within these U.-shaped'projections 46 is a movable lock bar 47'having circular. apertures 48 therein, the lock bar being movable sothat'the upper end thereof may proiect through apertures 42 or. 43 in the disk 39, the circular apertures 43 in the lock bar 47 being placed so as to register with the openings between the U shaped' projections 46 when the upper end of the lock bar is within either of the apertures 42 or 43'.

Plate 45 carries a pair of arms 50 which extend through the door 2 andfproiect' beyond the. interior surface thereof, a latch 51 having a latching tip 52 being pivotally supported between these, arms and biased to the position shown in Figure 2 by a spring. 53 interposed betweendoor 2" and latch 51:. Figure Z'shows that the normal position oflatch tip 52 is immediately behind plate 33. An aperture/54 is provided through plate 45 and the surface of door 2 so that, as subsequently explained, a disabling. tool may be'used to eff'ect'disengagement of latch tip 52' from plate 33. I

If desired, a second latch device may be provided of the type shown in Figures 1 and 3, so that door 2 will be normally latched and may be locked closed regardless of the" condition of latch 51.

A- modification of the operating mechanism explained above is shown in Figures l and 11 in which there is shown an automatic electric circuit breaker 55 having an operating handle 56 therefor, the circuit breaker being mounted on the back of the enclosing box and being of the type having inherent overcenter action, such as shown in Patent No. 2,426,880. In this modification, brackets 57 and 58, which are suitably secured to the circuit break-, er, mount a vertical supporting member 59 in which operating shaft 61 is pivotally secured, the brackets 57 and 58 having horizontal flanges 60, provided with slots through which extends an operator 62 for the circuit. breaker handle 56, the handle 56 fitting within a U-shaped socket in the member 62 as may be seen by an inspection of. Figure 11.

Fixedly mounted to the shaft 61 by means of a pin 63 which projects through the shaft is a lever 64 similar to lever Sof Figure 2. Lever 64 has a ledge 65 which is.

suitably secured. to one end of compression spring 66, the. other. end of spring 66 abutting against a projecting ledge 67 of a lever 68 pivotally mounted upon the shaft 61, lever. 68 having a second ledge 69 which fits over and normally against ledge 65 of lever 64 in the position of the parts shown in Figure 10. Lever 68 carries an on:

crating pin 72 which projects through a suitable slot 73 in the operator 62. The coupling members and the mechanism associated with the door are, of course, as previously described.

' The operation ofthe device of Figures l9-. will now bev described. As the door 2 of the enclosing box 1 is closed, the configuration of'eoupling members. 29 and 35, as, previously indicated, will cause any necessary rotation of handle 41 to engage bosses 32 in slots 36. As this connection is made, handle 41, if in normal intermediate position, automatically is. rotated to the on or "off position, depending upon the condition of the enclosed device, against the bias of spring 44, and latch tip 52 of latch. 51 is moved behind the. arcuate plate 33. Aperture 34in plate 33 is positioned along the periphery thereof so that when operating. shaft 7 (or. shaft 61) has moved the circuit controlling instrumentality to the off position, tip 52 of latch 51 is aligned with aperture 34, as may be seen in Figure 6 In any other position of the operating handle, tip 52 of latch 51 abuts against plate 33 thereby preventing opening of the door 2. In the off position, tip, 52 passes freely through aperture. 34 and the door 2 may be opened providing, of course, that any auxiliary latching mechanism such as that shown in Figure 3, has been released.

Movement of handle 41 from the position shown in Figure 2 toward the on position effects movement of operating shaft 7, and lever 8 which rotates therewith effects movement of lever 15by virtue of the connection betweenprojections 12.and 16, as may be seen in. Figure 4.

Lever 15 takes up any lost motion and then moves drive pin 26, attached to. toggle plate 25., upwardly from the position shown in Figure 4 until spring 24 is moved by toggle link 23 past its overcenter position. Spring 24 then effects a very rapid further upward movement of drive pin 26 to effect a snap action of lever 17 about its pivot. As pin 26 moves, it also takesup lost motion with respect to lever 17. Lever 17 then carries lever 19, and the connection between lever 19 and lever 21, rapidly downwardly from the position shown in Figure 2 to effect a quick movement of bail 18 to close the contact blade 4 upon contact 55 and close the switch.

Door 2 of enclosing box 1 may not then be opened as latch tip 52 is not positioned in front of aperture 34 in plate 33, but rather engages portion 28 thereof. If, however, it should become desirable to open door 2 when the circuit controlling instrumentality is'in the on position, a disabling tool may be inserted through aperture 54 to effect rotation of latch 51 about its pivot and against the bias of spring 53, moving latch tipv 52 clear of member 33. Latch 51 will then not impede the opening of the. doorf2. 'With the operating handle 41 in the on position, aperture 42 in disk 39 is positioned immediately above. locking bar 47. If it should become necessary to. prevent unauthorized opening of door 2 of the enclosure 1, lack bar 47 may be moved upward, and the upper tip inserted into aperture 42 and a lock inserted through one of the circular holes 48, which will, in this position of the. lock bar, be between the projection 46. It is apparent that in this position of lock bar 47, aperture 54 is blocked and no. access may be had to the latch 51 through the aperture, 5'4. Also, the handle is locked in on position.

Upon lowering of the lock bar 47 out of contact with disk 39, operating handle 41 may again be moved back to the position shown in Figure 2, the operating shaft moving lever 8 which compresses spring 13, which then effects movement of lever 15 by virtue of its connection with the ledge 14 thereof. Lever 15, again, effects movement of drive pin 26 to toggle plate 25, carrying toggle. link 23 past its overcenter position, whereby overcenter spring 24 effects a very rapid switch opening operation.

As previously indicated, with the operating handle in the off position, latch tip 52 of latch 51 is positioned immediately behind aperture 34 in member 33, so. that the. door 2 may be opened. If it is desired, however, that such opening be prevented except by authorized persons, operating handle. 41 may be moved beyond the off" position, rotating shaft 7 counterclockwise from the posi tion shown in Figure 4. The ledge 12 of lever 8 will move downward against the bias of compression spring 13, handle 4.1 being moved until aperture 43 of disk 39 is immediately above lock bar 47. In this position, latch tip 52 is behind portion 27 of plate 33. Lock bar 47 may then be raised, the. tip thereof passing into aperture 43 and, as previously described, lockedin this position by a lock hasp as shown in Figure 12. As previously indicated, with the lock bar 47 in its raised position, no access to latch 51 may be had through aperture. 54, the door therefor being held closed until. such time as an authorized person will remove the lock and permit lock bar 47 to return to the position indicated in Figure, 2. As soon as the lock bar is removed, spring 13 will effect movement of handle 41 back to the off position, in which latch tip 52 registers with aperture 34.

The operation of the circuit breaker of Figures 10 and l i will be readily apparent from the foregoing description. the operating handle 41 being rotated to on and off positions to effect movement of operating shaft 61. The mechanism for locking door 2 closed is, of course, the same with the circuit breaker as it was with the switch. Rotation of shaft 61 effects movement of lever 64- which, by virtue of its ledge 65, transmits its motion to lever 68. From the view of Figure 10, counterclockwise rotation of shaft 61 will force ledge 65 against ledge 69 of lever 63 to rotate the lever counterclockwise and move pin 72 upwardly to raise member 62, thus moving handle 56 of circuit breaker 55 to the on position. Clockwise rotation of shaft 61 forces ledge 65 of lever 64 against spring 66, the spring 66 effecting motion of lever. 63 by virtue of its connection with ledge 67 thereof. Upon the occurrence of overload and short circuit currents, circuit: breaker 55 is automatically moved to off position as explained in the aforesaid Patent No. 2,426,880. Handle 56 then automatically moves to a position intermediate its onand off positions. This movement of. handle 56.

from the on position will effect movement of operator 62 downwardly and through the interconnecting levers will move operating handle 41 to a position intermediate its on and off positions to effect an indication of the automatic trip condition of the circuit breaker.

To reset the circuit breaker after automatic operation, operating handle 41 is rotated clockwise beyond the off position, whereupon the internal circuit breaker parts are reset so that future movement of operating handle 41 to on position will effect closing of the circuit breaker as previously described. It will therefore be seen that the reset and lock-off" positions of operating handle 4-1 are substantially the same.

It will be readily apparent that the device of the present invention is a new and improved mechanism for operating enclosed circuit controlling instrumentalities in which the instrumentality is mounted within an enclosure having an openable door, the device being so arranged and constructed that the operating handle may be moved to either the on or the off position, with the door readily openable in off position, and openable by manipulation in the on position, and in which means are provided to lock the operating handle in a position such that the circuit controlling instrumentality may either be on or off, and with the door to the enclosure for the instrumentality locked against opening except by authorized personnel, this being accomplished by but a single lock, if desired.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. In a device for enclosing and operating a circuit controlling instrumentality having a movable actuator, a casing in which said instrumentality is mounted, an openable cover for said casing having an operating handle thereon movable to a plurality of positions including on, off and a third position, means connecting said operating handle to said movable actuator whereby movement of said operating handle effects movement of said actuator to effect operation of said instrumentality, said connecting means including lost motion means so that no substantial movement of said movable actuator occurs as said operating handle is moved from said off to said third position, means disposed behind said cover for locking said cover in closed position, said locking means being associated with said operating handle so as to be rendered ineffective by movement of said operating handle to said off position, an aperture in said cover through which a suitable tool may be inserted to normally render said locking means ineffective in any position of said operating handle, and single means on the front side of said cover for holding said operating handle in said on or third position and simultaneously preventing access to said locking means through said aperture to thereby prevent said locking means from being released.

2. In a device for enclosing and operating a circuit controlling instrumentality having a movable actuator, a casing in which said instrumentality is mounted, an openable cover for said casing having an operating handle thereon movable to a plurality of positions including on, off and a third position, means connecting said oper ating handle to said movable actuator whereby movement of said operating handle effects movement of said actuator to effect operation of said instrumentality, said connecting means including lost motion means so that no substantial movement of said movable actuator occurs as said operating handle is moved from said off to said third position, means for locking said cover in closed position, said locking means being associated with said operating handle so as to be rendered ineffective by movement of said operating handle to said off position, an aperture in said coverthrough which a suitable tool may be passed to render said locking means ineffective in any position of said operating handle, and

said bar may be locked in a locking position to prevent operation of said operating handle and opening of said cover.

3. In a device for enclosing and operating a circuit controlling instrumentality having a movable actuator, a casing in which said instrumentality is mounted, an openable cover for said casing having an operating handle thereon movable to a plurality of positions including on, off and a third position, means including an operating shaft connecting said operating handle to said movable actuator whereby movement of said operating handle effects movement of said actuator to effect operation of said instrumentality, said connecting means including lost motion means so that no substantial movement of said movable actuator occurs as said operating handle is moved from said off to said third position, locking means behind said cover including a latching surface on said operating shaft and a biased latch on the inner surface of said operable cover, means for rendering said locking means ineffective by movement of said operating handle to said off position, an aperture in said cover through which a suitable tool may be passed to move said latch against its bias to render said lockingmeans ineffective in any position of said operating handle, and means on said front cover comprising a sliding bar aligned with said aperture for locking said operating handle in said on and third positions, said bar blocking access to said locking means through said aperture when said bar is in locking position, and means on the front of said cover cooperating with said locking bar whereby said bar may be locked in locking position to prevent operation of said operating handle and opening of said cover.

4. In a device for enclosing and operating a circuit controlling instrumentality having a movable actuator, a casing in which said instrumentality is mounted, an openable cover for said casing having an operating handle thereon movable to a plurality of positions including on, off and a third position, means including an operating shaft connecting said operating handle to said movable actuator whereby movement of said operating handle effects movement of said actuator to effect operation of said instrumentality, said connecting means effecting no substantial movement of said movable actuator as said operating handle is moved from said off to said third poistion, locking means for said cover comprising a latching plate rigidly mounted to said operating shaft and a spring biased latch inside of said cover having a latching tip normally engaging said latching plate, said latching plate having an aperture therein positioned to register with said latching tip when said operating handle is in said off position whereby said locking means is rendered ineffective, an aperture in said cover through which a suitable tool may be passed to move said latch against its bias to disengage said latching tip from said plate to render said locking means ineffective, and means on said front cover for preventing movement of said operating handle and for blocking access to said latch through said cover aperture comprising an elongated sliding bar aligned with said cover aperture, said bar engaging said handle and blockingaccess to said locking means through said cover aperture when said bar is in locking position, and means on said cover cooperating with said locking bar whereby said bar may be locked in locking position to prevent operation of said operating handle and opening of said cover.

5. In a device for enclosing and operating a circuit controlling instrumentality having a movable actuator, a casing in which said instrumentality is mounted, an openable cover for said casing having an operating handle thereon movable to a plurality of positions including on, off and a third position, said operating handle being movable to said third position only through said off position, an operating shaft, means for connecting in all positions of said operating handle except the off 7 position, means accessible from the exterior of the closed casing for rendering said locking means ineffective in any position of said operating handle, a single means on the outside surface of said cover for holding said operating handle in said on or third. positions and for simul taneously preventing said locking means from being rendered ineffective, whereby said operating shaft may be locked in either its on or third position and said cover simultaneously maintained locked until said single means is released.

6. In a device for enclosing and operating a circuit controlling instrumental'ity having a movable actuator, a casing in which said instrumentality is mounted, an openable cover for said casing having an operating handle thereon movable to a plurality of positions including on, off and a third position, said operating handle being. movable to said third position only through said *otf" position, an operating shaft, means for connecting said operating shaft to said handle whereby said shaft is movable in response to handle movement, means for operating said actuator in response to movement of said shaft, said last mentioned means including a first lever rigidly mounted to said operating shaft, a second lever, and resilient means interposed between said first and second levers, said resilient means absorbing the movement of said shaft as said handle is moved from said off to said third position whereby said actuator is not substantially moved during this movement of the handle, means for locking said cover in closed position, said locking means being associated with said operating handle so as to be rendered ineffective by movement of said operating handle to said off position, means accessible from the exterior of the closed casing for rendering said locking means ineffective in any position of the operating handle, and a single means on the outside surface of said cover for holding said operating handle in said on and third positions and for simultaneously preventing said locking means from being released whereby said operating shaft may be locked in either its on or third positions and said cover simultaneously maintained locked until said single means is released.

7. In a device for enclosing and operating a circuit controlling instrumentality having a movable actuator, a casing in which said instrumentality is mounted, an openable cover for said casing having an operating handle thereon movable to a plurality of positions including on, off and a third position, said operating handle being movable to said third position only through said 01f position, an operating shaft, means for connecting said operating shaft to said handle whereby said shaft is movable in response to handle movement, means for operating said actuator in response to movement of said shaft, said last mentioned means including resilient means which absorbs the movement of said shaft as said handle is moved from said off to said third position whereby said actuator is not substantially moved during this movement of said handle, means disposed behind said cover for locking said cover in closed position, said locking means being associated with said operating handle and rendered ineffective by movement of said operating handle to said oif position, an aperture in said cover through which a suitable tool may be inserted to normally render said locking means ineffective in any position of said operating handle, and means on the front side of said cover for locking said operating handle in said 011" or third positions and preventing access to said locking means through said aperture to thereby simultaneously prevent said locking means from being released when said handle is locked so that said shaft is maintained in either its on or third position and said cover is maintained under the control of said locking means until said handle is unlocked.

8. In a device for enclosing and operating a circuit controlling instrumentality having a movable actuator, a casing in which said instrumentality is mounted, an openable cover for said casing having an operating handle thereon movable to a plurality of positions including on, off and a third position, said operating handle being movable to said third position only through said off position, an operating shaft, means for connecting said operating shaft to said handle whereby said shaft is movable in response to handle movement, means for operating said actuator in response to movement of said shaft, said last mentioned means including resilient means which. absorbs the movement of. said. shaft as said: handle is moved from said, oiff to said third position whereby said actuator is not substantially moved. during thismovement of said handle, locking means: behind said cover including a latching surface on said operating shaft and a biased latch on the inner surface of said: front cover, means rendering said locking means ineffective; by move. ment of said operating handle to, said: off position, an aperture in said cover through which a suitable. tool; may be passed to render said locking means; ineffective in any position of said operating handle, and: means: on said front cover comprising a sliding bar aligned: with said aperture for locking said operating handle i'nsaid: on and third positions, said: bar blocking accesstto said locking means through said aperture when, said bar is in locking position, and means on the front: of said cover cooperating with said locking bar whereby said ban. may be locked in locking position to prevent. simultaneously both operation. of said operating handie and: opening of said cover so that said actuator is locked in either on or off position and: said cover istsimui -i taneously locked closed. until said locking bar is; released.

9. In a device for enclosing and: operating acircuitcontrolling instrumentality having a movable actuator, a casing in which said instrumentality is mounted, an open-. able cover for said casing having. an ,:operating handle: thereon movable to a plurality of positions including on, off and a third position, said' operating hand-1eI being movable to said third position only through said off position, an operating shaft, means; for connectingsaid operating shaft to said handle. whereby said shaft is movable in response to handle movement, means for operating said actuator in response. to movement of said. shaft, said last mentioned means including a first lever rigidly mounted to said operating shaft, 21 second lever, and resilient means interposed, between said first and second levers, said resilient mean-s absorbing the. move, ment of said shaft as said handle. is moved from said. off to said third position whereby said actuator is not substantially moved. during this; movement of said handle, locking means for said cover comprising a latching plate rigidly mounted to said. operating shaft and a spring biased latch inside of said. cover having a latching tip. normally engaging said. latching plate, Said latching plate having an aperture therein positioned to register with said latching tip upon movement of said operating handle to said off position whereby said locking means is rendered ineffective, an aperture in said" cover through which a suitable tool may be passed to move said latch against its bias to disengage said latching tip from said plate to render said locking means ineffective, and means on said front cover for preventing movement of said operating handle and for blocking access to said. latch through said cover aperture comprising an elongated sliding bar aligned with said cover aperture, said bar blocking access to said locking means through said cover aperture when said bar is in locking position, and means on said cover cooperating with said locking. bar whereby said bar may be locking in locked position to prevent operation of said operating handle or opening of said cover.

10. In a device for enclosing and operating a circuit controlled instrumentality having a movable actuator, a casing in which said instrumentalityis mounted, an open able cover for such casing having an operating handle thereon movable to a plurality of positions including on, off and a third position, said third position being on the side of said off position opposite the on position, means including an operating shaft connecting said operating handle to said movable actuator whereby movement of said operating handle effects movement of said actuator to effect operation of said instrumentality, said connecting means including lost motion means so as to effect no substantial movement of said movable actuator as said operating handle is moved from. said off to said third position, locking means for said cover comprising a latching plate rigidly mounted to said operating shaft and a spring biased. latch on the inside surface of said cover having a latching tip normally engaging saidv latching plate, said latching plate having an aperture therein positioned to register with said latching tip when said operating handle is in said off position whereby said locking means. is rendered: ineffective, an aperture in said cover through which. a

suitable tool may be passed to move said latch against its bias to disengage said latching tip from said latching plate and thereby render said locking means ineffective, and means on the outside surface of said cover for preventing movement of said operating handle and for blocking access to said latch through said cover aperture comprising an elongated sliding bar aligned with said cover aperture, said bar engaging said handle and blocking access to said locking means through said cover aperture when said bar is in locking position, and means on said cover cooperating with said locking bar whereby said bar may be locked in locking position to prevent operation of said operating handle and opening of said cover.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,260,073 Ellis Oct. 21, 1941 2,467,307 Hammerly Apr. 12, 1949 2,475,338 Rowe July 5, 1949 2,512,505 Rowe June 20, 1950 2,550,125 Schueler et al. Apr. 24, 1951 

